Proteinaceous microstructure in a capillary: a study of non-linear bending dynamics

Area of Science:

• Microfluidics
• Biomaterials Science
• Soft Matter Physics

Background:

• Flapping of flexible structures under flow is crucial in energy harvesting and microfluidic mixing.
• Microscale bending dynamics of such structures remain under-investigated.
• Understanding these dynamics is key for developing novel micro-devices.

Purpose of the Study:

• To fabricate and characterize the bending dynamics of microscale flexible structures.
• To investigate the influence of material properties and cross-sectional geometry on dynamics.
• To explore potential applications in energy conversion.

Main Methods:

• Two-photon laser polymerization for fabricating proteinaceous microstructures within micro-capillaries.
• Atomic Force Microscopy for testing elastic properties.
• Microfluidic experiments at intermediate Reynolds numbers (Re ≲ 150) to study deflection-flow dependence.

Main Results:

• Fabricated microstructures with Young's modulus (100 kPa ≤ E ≤ 4 MPa) comparable to biological tissues.
• Elastic constants (0.8 nN μm⁻¹ ≤ k ≤ 50 nN μm⁻¹) align with Euler Bernoulli theory.
• Soft microstructures (k ≤ 8 nN μm⁻¹) showed undamped bending oscillations (~10% deflection) due to viscoelasticity and non-linear dynamics.

Conclusions:

• Microstructure bending dynamics are tunable via laser fabrication intensity.
• Undamped oscillations in soft microstructures reveal complex fluid-structure interactions.
• These findings pave the way for developing novel energy conversion nanoplatforms.